diff --git a/server/cache_util/memcache.py b/server/cache_util/memcache.py
index 15ed9f080..0965c1880 100644
--- a/server/cache_util/memcache.py
+++ b/server/cache_util/memcache.py
@@ -33,8 +33,8 @@ class MemCache(cachetools.Cache):
     """Use memcached as the backing cache."""
 
     def __init__(self, url='127.0.0.1', username=None, password=None,
-                 missing=None, getsizeof=None, mustBeAvailable=False):
-        super(MemCache, self).__init__(0, missing, getsizeof)
+                 getsizeof=None, mustBeAvailable=False):
+        super(MemCache, self).__init__(0, getsizeof=getsizeof)
         if isinstance(url, six.string_types):
             url = [url]
         # pylibmc used to connect to memcached client.  Set failover behavior.
diff --git a/setup.py b/setup.py
index d7058b31e..378662841 100644
--- a/setup.py
+++ b/setup.py
@@ -2,6 +2,7 @@
 # -*- coding: utf-8 -*-
 
 import json
+import platform
 
 try:
     from setuptools import setup
@@ -55,7 +56,7 @@
     ],
     include_package_data=True,
     install_requires=[
-        'cachetools>=2.0.0',
+        'cachetools>=3.0.0',
         'enum34>=1.1.6',
         'jsonschema>=2.5.1',
         'libtiff>=0.4.1',
@@ -67,8 +68,8 @@
     ],
     extras_require={
         'memcached': [
-            'pylibmc>=1.5.1;platform_system!="Windows"'
-        ],
+            'pylibmc>=1.5.1'
+        ] if platform.system() != 'Windows' else [],
         'openslide': [
             'openslide-python>=1.1.0'
         ],